lio 



Mr Lahy, A string electrometet. 



limit, as will be explained later, to the sensitiveness that may be 

 obtained by increasing the potential difference, or decreasing the 

 tension. With the plates at this distance apart the position of 

 the fibre was plotted against its voltage and the curve of fig. 4 

 obtained. It will be observed that one of these graphs is a 

 straight line, so that the deflection is proportional to the voltage 

 even for high sensitiveness, and for a wide range (for an electro- 

 scope) of voltages. 



50 r 



•2 -4 -6 



Potential of fibre in volts 



1-0 



1-2 



1-4 



Fig. 4. 



Plates near together {<6'Q mm. and 3'3 mm.). When the dis- 

 tance between the plates was reduced to 6'6 mm. and finally 

 to 3'3 mm. several properties of the instrument, to be seen in 

 figs. 3 and 5, came into greater evidence. 



The chief change in the potential difference-sensitiveness 

 curves (fig. 3, plates at 6'67 mm.) is that smaller p.d.'s appear to 



